1) Field of the Invention
The present invention relates to a device for the command of the electrical power supply of a plurality of local electrical apparatuses from a single central source of direct current, and more particularly to a central bistable switch connected between a first terminal of said source and the power supply lines of said local electrical apparatuses and a central resistor connected in parallel with said central switch, each local electrical apparatus comprising a local resistor and at least one switch in series, which are connected between its power supply line and the second terminal of said source, each local resistor forming, together with the central resistor, a voltage divider bridge, the center tap of which is connected to a central detector controlling said central switch, each local electrical apparatus supplying to the central detector with information for reopening the power supply central switch. The invention is applied, in particular, to the power supply of the various electrical apparatuses of a motor vehicle from a central power supply unit.
2) Discussion of Related Art
In devices of known type, which are described, for example, in French Patent 2,596,216, the central unit remains in the standby condition and can be activated by the actuation of the local control switch by means of the aforementioned divider bridge, the median voltage of which is detected by the central detector, which "activates" the central unit in the event of a demand expressed by the actuation of a local control switch. This device permits control of the power supply of the local electrical apparatuses only when one of them is used and permits limiting, to a minimum, of the consumption losses when none of the electrical apparatuses is being used. However, in the standby condition, there remains leakage currents circulating through the central resistor and the leakage impedances of said apparatuses.